Hormonal influences on the binding and metabolism of estradiol in human endometrium will be studied in vitro. For this purpose, fragments of tissue kept under organ culture conditions or monolayers of endometrial epithelial and stromal cells will be used. Inductibility of estradiol 17 beta dehydrogenase by progestins in tissue fragments and monolayers derived from proliferative endometrium will be compared. Culture conditions for optimal response will be defined. Metabolism of progesterone and androgens will be characterized in vitro in proliferative and secretory endometrium and formation of metabolites in glandular and stromal cells will be compared. The nature of estroadiol binding sites in nuclei from human endometrium which can be labeled at 0 degree C will be investigated by evaluating their concentration, extractability specificity, and sedimentations characteristics. A superfusion system for the study of uptake and metabolism of steroid hormones in homogenous cell suspensions will be developed. In vivo experiments will be conducted in rabbits to determine whether estrone sulfate can be taken up and metabolized directly by the uterus without prior conversion to circulating unconjugated estrogens.